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<H2><A NAME="s4">4.</A> <A HREF="partiview.html#toc4">Commands</A></H2>
<P>There are two types of commands in <CODE>partiview</CODE>:
Control Commands and Data Commands.
Probably the most visible difference between the two is that every Control
Command returns feedback to the user, whereas Data Commands
are interpreted without comment unless an error occurs.</P>
<P>Some situations, e.g. the command-entry text box, expect to receive
Control Commands; others, e.g. files (.cf, .speck, etc.) named on
the command line or specified by <CODE>read</CODE> or <CODE>include</CODE> commands,
are expected to contain Data Commands.</P>
<P>However, it is always possible to enter a Data Command
where a Control Command is expected,
using the <CODE>add</CODE> command prefix, e.g. you could type in the text box:
<BLOCKQUOTE><CODE>
<HR>
<PRE>
add 0 0 0 text The Origin
</PRE>
<HR>
</CODE></BLOCKQUOTE>
. Likewise, a Control Command
may be given where data is expected, as in a data or .cf file,
using the <CODE>eval</CODE> prefix:
<BLOCKQUOTE><CODE>
<HR>
<PRE>
1 0 0 text X=1
eval bgcolor 0.3 0.2 0.1
</PRE>
<HR>
</CODE></BLOCKQUOTE>
</P>
<P>See also the previous <B>starlab</B> example.</P>
<H2><A NAME="ss4.1">4.1</A> <A HREF="partiview.html#toc4.1">Control Commands</A>
<P>(see partibrains.c::specks_parse_args)</P>
<P>Control Commands are accepted in the Command window, and in some other contexts.
Generally, <CODE>partiview</CODE> gives a response to every Control Command,
reporting the (possibly changed) status.</P>
<P>Typically, if parameters are omitted, the current state is reported.</P>
<P>Some commands apply to particles in the current group (see Object group commands);
others affect global things, such as time or display settings.</P>
<P>Data Commands can also be given, if prefixed with <CODE>add</CODE>.</P>
<H2><A NAME="ss4.2">4.2</A> <A HREF="partiview.html#toc4.2">I/O Control Commands</A>
<DT><B>read <I>specks-file</I></B><DD><P>Read a file containing Data Commands (typical suffix <CODE>.cf</CODE> or <CODE>.speck</CODE>).</P>
<DT><B>async <I>unix-command</I></B><DD><P>Run an arbitrary unix command (invoked via /bin/sh) as a subprocess of <CODE>partiview</CODE>.
Its standard output is interpreted as a stream of control commands.
Thus <CODE>partiview</CODE> can be driven externally, e.g. to record an animation
(using the <CODE>snapshot</CODE> command), or to provide additional GUI controls.
Several <CODE>async</CODE> commands can run concurrently.
Examples are given later. Warning: you cannot interrupt a started command,
short of hitting ESC to exit partiview.</P>
<DT><B>add <I>data-command</I></B><DD><P>Enter a Data Command where a Control Command is expected,
e.g. in the text input box. For example,
<PRE>
add 10 15 -1 text blah
</PRE>
adds a new label "blah" at 10 15 -1, or
<PRE>
add kira myrun.out
</PRE>
loads a kira (starlab) output file.</P>
<DT><B>eval <I>control-command</I></B><DD><P>Processes that control command just as if the <CODE>eval</CODE> prefix weren't there.
Provided for symmetry: wherever either a control command or a data command
is expected, entering <CODE>eval</CODE> <I>control-command</I> ensures that it's
taken as a control command.</P>
<DT><B>add filepath (data-command)</B><DD><P>Determines the list of directories where all data files, color maps, etc.
are sought. See the <CODE>filepath</CODE> entry under
Data Commands.</P>
</P>
<H2><A NAME="ss4.3">4.3</A> <A HREF="partiview.html#toc4.3">Object Group Control Commands</A>
<P><CODE>Partiview</CODE> can load multiple groups of particles,
each with independent display settings, colormaps, etc.
When more than one group is loaded, the Group Row appears on the GUI,
with one toggle-button for each group. Toggling the button turns
display of that group on or off. Right-clicking turns the group unconditionally on,
and selects that group as the current one for other GUI controls.</P>
<P>Many Control Commands apply to the <I>currently selected</I> group.</P>
<P>Groups always have names of the form g<I>N</I> for some small positive <I>N</I>;
each group may also have an alias.</P>
<DT><B>g<I>N</I> </B><DD><P>Select group g<I>N</I>. Create a new group if it doesn't already exist.</P>
<DT><B>g<I>N</I>=<I>alias</I> </B><DD><P>Assign name <I>alias</I> to group g<I>N</I>.
Note there must be no blanks around the <CODE>=</CODE> sign.</P>
<DT><B>object <I>objectname</I></B><DD><P>Likewise, select object <I>objectname</I>, which may be either an alias name
or g<I>N</I>. </P>
<DT><B>g<I>N</I> <I>control-command</I></B><DD>
<DT><B>object <I>objectname</I> <I>control-command</I></B><DD><P>Either form may be used as a <I>prefix</I> to any control command
to act on the specified group, e.g. <CODE>object fred poly on</CODE></P>
<DT><B>gall <I>control-command</I></B><DD><P>Invoke the given <I>control-command</I> in all groups.
For example, to turn display of group 3 on and all others off, use:
<BLOCKQUOTE><CODE>
<PRE>
gall off
g3 on
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B>on</B><DD>
enable the display of the currently selected group (as it is by default).</P>
<DT><B>off</B><DD>
<DT><B>disable</B><DD><P>Either one will turn off the display of the current group.</P>
</P>
<H2><A NAME="ss4.4">4.4</A> <A HREF="partiview.html#toc4.4">View Control commands</A>
<P>View commands affect the view; they aren't specific to data groups.</P>
<DT><B>fov <I>float</I></B><DD><P>Angular field of view (in degrees) in Y-direction.</P>
<DT><B>cen[ter] <I>X Y Z</I> [<I>RADIUS</I>]</B><DD><P>Set point of interest. This is the center of rotation in
<CODE>[o]rbit</CODE> and <CODE>[r]otate</CODE> modes. Also, in <CODE>[o]rbit</CODE> mode,
translation speed is proportional to the viewer's distance from this point.
The optional <I>RADIUS</I> (also set by <CODE>censize</CODE>) determines the size
of the marker crosshair, initially 1 unit.</P>
<DT><B>cen[ter] [<I>X Y Z</I> [<I>RADIUS</I>]]
int[erest] [<I>X Y Z</I> [<I>RADIUS</I>]]</B><DD><P>Set point of interest. This is the center of rotation in
<CODE>[o]rbit</CODE> and <CODE>[r]otate</CODE> modes. And, in <CODE>[o]rbit</CODE> mode,
translation speed is proportional to the viewer's distance from this point.
The optional <I>RADIUS</I> (also set by <CODE>censize</CODE>) determines the size
of the marker crosshair, initially 1 unit.</P>
<P>**** why is center/interest commented out in the first example. Originally
this command was documented twice, the first one has /interest commented out.</P>
<DT><B>censize [<I>RADIUS</I>]</B><DD><P>Set size of point-of-interest marker.</P>
<DT><B>where <I>(also)</I> w</B><DD><P>Report the 3-D camera position and forward direction vector.</P>
<DT><B>clip <I>NEAR</I> <I>FAR</I></B><DD><P>Clipping distances. The computer graphics setup always requires
drawing only objects in some finite range of distances in front of the
viewpoint. Both values must be strictly positive, and their ratio
is limited; depending on the graphics system in use, distant objects
may appear to blink if the <I>FAR</I>/<I>NEAR</I> ratio exceeds 10000 or so.</P>
<P>To set the far clip range without changing the near, use a non-numeric
near clip value, e.g. <CODE>clip - 1000</CODE>.</P>
<DT><B>jump [<I>X Y Z</I>] [<I>Rx Ry Rz</I>]</B><DD><P>Get or set the current position (XYZ) and/or viewing (RxRyRz) angle.</P>
<DT><B>readpath</B><DD><P>Read a Wavefront (<CODE>.wf</CODE>) file describing a path through space.</P>
<DT><B>rdata</B><DD><P>Synonym for readpath.</P>
<DT><B>play <I>speed</I>[f]</B><DD><P>Play the currently loaded (from <CODE>readpath</CODE>/<CODE>rdata</CODE>) camera animation
path, at <I>speed</I> times normal speed,
skipping frames as needed to keep up with wall-clock time.
(Normal speed is 30 frames per second.)
With "f" suffix, displays every <I>speed</I>-th frame, without regard to real
time.</P>
<DT><B>frame [<I>frameno</I>]</B><DD><P>Get or set the current frame the <I>frameno</I>-th.</P>
<DT><B>update </B><DD><P>Ensures the display is updated, as before taking a snapshot.
Probably only useful in a stream of control commands from an <CODE>async</CODE>
subprocess.</P>
<DT><B>winsize [<I>XSIZE</I> [<I>YSIZE</I>]]</B><DD>
<DT><B>winsize <I>XSIZE</I>x<I>YSIZE</I>+<I>XPOS</I>+<I>YPOS</I></B><DD><P>Resize graphics window. With no arguments, reports current size.
With one argument, resizes to given width, preserving aspect ratio.
With two arguments, reshapes window to that height and width.
With complete X geometry specification (no embedded spaces),
e.g. <CODE>winsize 400x350+20-10</CODE>,
also sets position of graphics window, with +X and +Y measured from
left/top, -X and -Y measured from right/bottom of screen.</P>
<DT><B>detach [full|hide] [<I>+XPOS+YPOS</I>]</B><DD><P>Detach graphics window from GUI control strip and optionally
specify position of control strip. With <CODE>full</CODE> or <CODE>hide</CODE>,
makes graphics window full-screen with GUI visible or hidden, respectively.
With neither <CODE>full</CODE> nor <CODE>hide</CODE>, the graphics window
is detached but left at its current size.</P>
<P>The <I>+XPOS+YPOS</I> is a window position in X window geometry style,
so e.g. <CODE>detach full -10+5</CODE> places the GUI near the
upper right corner of the screen, 10 pixels in from the right
and 5 pixels down from the top edge.</P>
<P>If you don't mind typing blindly, it's still possible to enter
text-box commands even with the controls hidden;
press the <I>Tab</I> key before each command to ensure that
input focus is in the text box.
Use <I>Tab</I><CODE>detach full</CODE><I>Enter</I>
to un-hide a hidden control strip.</P>
<DT><B>bgcolor <I>R G B</I></B><DD><P>Set window background color (three R G B numbers or one grayscale value).</P>
<DT><B>focallen <I>distance</I></B><DD><P>Focal length: distance from viewer to a typical object of interest.
This affects stereo display (see below) and navigation: the speed of
motion in <CODE>[t]ranslate</CODE> and <CODE>[f]ly</CODE> modes is proportional to this
distance.</P>
<DT><B>stereo [on|off|redcyan|glasses|cross|left|right] [<I>separation</I>]</B><DD><P>Stereo display. Also toggled on/off by typing <CODE>'s'</CODE> key in graphics window.
Where hardware allows it, <CODE>stereo glasses</CODE> selects
CrystalEyes-style quad-buffered stereo. All systems should be capable of
<CODE>stereo redcyan</CODE>, which requires wearing red/green or red/blue glasses,
and of <CODE>cross</CODE> (crosseyed), which splits the window horizontally.
<CODE>left</CODE> and <CODE>right</CODE> show just that eye's view,
and may be handy for taking stereo snapshots.</P>
<P>Useful <I>separation</I> values might be 0.02 to 0.1, or -0.02 to -0.1 to swap
eyes. See also <CODE>focallen</CODE> command, which gives the distance to
a typical object of interest: left- and right-eye images of an object
at that distance will coincide on the screen.</P>
<P>Virtual-world eyes will be separated by distance
2 * <I>focallen * separation</I>, with convergence angle
2 * <CODE>arctan(</CODE><I>separation</I><CODE>)</CODE>.</P>
<P>See also the <CODE>winsize</CODE> and <CODE>detach</CODE> commands
for control over graphics window size and placement.</P>
<P>Beware: some systems which support hardware ("glasses")
stereo also require that the display be set to a
stereo-capable video mode. Partiview does not do this
automatically. For example, on stereo-capable SGI Irix systems,
you may need to type (to a unix shell)
<CODE>/usr/gfx/setmon -n 1024x768_96s</CODE> to allow
stereo viewing and something like <CODE>/usr/gfx/setmon -n 72</CODE>
to revert. Otherwise, turning partiview's stereo on
will just show the left eye's view -- displacing the viewpoint
but nothing else.</P>
<DT><B>snapset [<CODE>-n</CODE> <I>FRAMENO</I>] <I>FILESTEM</I> [<I>FRAMENO</I>]</B><DD><P>Set parameters for future <CODE>snapshot</CODE> commands.
<I>FILESTEM</I> may be a printf format string with frame number as
argument, e.g. <CODE>snapset pix/%04d.ppm</CODE>, generating image names
of <CODE>pix/0000.ppm</CODE>, <CODE>pix/0001.ppm</CODE>, etc.
If <I>FILESTEM</I> contains no % sign, then <CODE>.%03d.ppm.gz</CODE> is
appended to it, so <CODE>snapset ./pix/fred</CODE>
yields snapshot images named <CODE>./pix/fred.000.ppm.gz</CODE> etc.</P>
<P>Frame number <I>FRAMENO</I> (default 0) increments with each snapshot taken.</P>
<DT><B>snapshot [<I>FRAMENO</I> | <I>FILENAME</I>]</B><DD><P>Capture a snapshot image of the current view.</P>
<P>Either give <CODE>snapshot</CODE> an explicit filename,
or else specify a file format string with <CODE>snapset</CODE>
and then let <CODE>snapshot</CODE> fill in the frame number.
With neither <I>FRAMENO</I> nor <I>FILENAME</I>,
<CODE>snapset</CODE> adds one to the previous frame number.</P>
<P><CODE>Partiview</CODE> generally invokes the ImageMagick program <CODE>convert(1)</CODE>,
which must be installed and be on the user's $PATH. <CODE>Convert</CODE> determines
the type of image (jpeg, sgi, bmp, etc.) based on the file suffix.</P>
<P><CODE>Convert</CODE> is not needed if the <CODE>snapset</CODE> <I>FILESTEM</I> ends in
<CODE>.ppm.gz</CODE> (invokes gzip rather than convert) or <CODE>.ppm</CODE>
(no external program required).</P>
</P>
<H2><A NAME="ss4.5">4.5</A> <A HREF="partiview.html#toc4.5">Particle Display Control Commands</A>
</H2>
<P>These commands affect how particles (in the current group) are
displayed.</P>
<P>
<DL>
<DT><B>psize <I>scalefactor</I></B><DD><P>All particle luminosities (as specified by <CODE>lum</CODE> command)
are scaled by the product of two factors:
a <I>lumvar</I>-specific factor given by <CODE>slum</CODE>,
and a global factor given by <CODE>psize</CODE>.
So the intrinsic brightness of a particle is
<I>value-specified-by-</I><CODE>lum</CODE>
* <I>slum-for-current-lumvar</I>
* <I>psize-scalefactor</I>.</P>
<DT><B>slum <I>slumfactor</I></B><DD><P>Data-field specific luminosity scale factor, for current choice of
<I>lumvar</I> as given by the <CODE>lum</CODE> command.
A <I>slumfactor</I> is recorded independently for each data field, so
if data fields <CODE>mass</CODE> and <CODE>energy</CODE> were defined, one might say
<BLOCKQUOTE><CODE>
<PRE>
lum mass
slum 1000
lum energy
slum 0.25
</PRE>
</CODE></BLOCKQUOTE>
having chosen each variable's <I>slumfactor</I> for useful display,
and then freely switch between <CODE>lum mass</CODE> and <CODE>lum energy</CODE>
without having to readjust particle brightness each time.</P>
<DT><B>ptsize <I>minpixels</I> <I>maxpixels</I></B><DD><P>Specifies the range of <I>apparent</I> sizes of points,
in pixels. Typical values might be <CODE>ptsize 0.1 5</CODE>.
The graphics system may silently impose an upper limit
of about 10 pixels.</P>
<DT><B>poly [on|off]</B><DD><P>Display polygons, or don't.</P>
<DT><B>polysize [<I>scalefactor</I>]</B><DD><P>Multiplier for polygon size. Default is zero (!), so you must
set polysize to something else before polygons will show up.</P>
<DT><B>polylumvar [<I>attrname</I> | <CODE>point-size</CODE>] [<CODE>area</CODE> | <CODE>radius</CODE>]</B><DD><P>Choose which attribute determines the radius of a particle's polygon.
By default, it is <CODE>point-size</CODE>, a pseudo-attribute which varies with
the brightness of points (so adjusting the slum slider scales polygons too).</P>
<P>Each polygon's 3-D radius is the <CODE>polysize</CODE> <I>scalefactor</I> times its particle's
given attribute (whether an actual particle attribute or <CODE>point-size</CODE>). Or,
if the <CODE>area</CODE> keyword is specified, then the radius is the square root
of attribute * scalefactor. <CODE>area</CODE> is useful if the attribute represents
a luminosity; in that case, the polygon total brightness (which is proportional
to its screen area) becomes proportional to the attribute / distance^2.</P>
<DT><B>polymin <I>minradius</I> [<I>maxradius</I>]</B><DD><P>Specify a minimum screen radius for polygons, in pixels.
If smaller than this, they are not drawn.</P>
<DT><B>color</B><DD><P>Specify how particles are colored.
Generally, a linear function of some data field of each particle
becomes an index into a colormap (see <CODE>cmap</CODE>, <CODE>cment</CODE>).
<DT><B> color <I>colorvar</I> [<I>minval maxval</I>] </B><DD><P>Use data field <I>colorvar</I> (either a name as set by <CODE>datavar</CODE>
or a 0-based integer column number) to determine color.
Map <I>minval</I> to color index 1, and <I>maxval</I> to
the next-to-last entry in the colormap (<I>Ncmap-2</I>).
The 0th and last (<I>Ncmap-1</I>) colormap entry are used for
out-of-range data values.</P>
<P>If <I>minval</I> and <I>maxval</I> are omitted, the actual range of
values is used.</P>
<DT><B> color <I>colorvar</I> exact [<I>baseval</I>] </B><DD><P>Don't consider field <I>colorvar</I> as a continuous variable;
instead, it's integer-valued, and mapped one-to-one with
color table slots. Data value <I>N</I> is mapped to
color index <I>N+baseval</I>.</P>
<DT><B> color <I>colorvar</I> -exact </B><DD><P>Once the <CODE>exact</CODE> tag is set (for a particular data-field),
it's sticky. To interpret that data field as a continuous, scalable
variable again, use <CODE>-exact</CODE>.</P>
<DT><B> color const <I>R G B</I> </B><DD><P>Show all particles as color <I>R G B</I>, each value in range 0 to 1,
independent of any data fields.</P>
</P>
<DT><B>lum</B><DD><P>Specify how particles' intrinsic luminosity is computed:
a linear function of some data field of each particle.
<DL>
<DT><B> lum <I>lumvar</I> [<I>minval maxval</I>] </B><DD><P>Map values of data field <I>lumvar</I> (<CODE>datavar</CODE> name or
field number) to luminosity.
The (linear) mapping takes field value <I>minval</I> to
luminosity 0 and <I>maxval</I> to luminosity 1.0.</P>
<P>If <I>minval</I> and <I>maxval</I> are omitted,
the actual range of values is mapped to the luminosity range
0 to 1.</P>
<P>Note that the resulting luminosities are then scaled by
the <CODE>psize</CODE> and <CODE>slum</CODE> scale factors, and further
scaled according to distance as specified by <CODE>fade</CODE>, to compute
apparent brightness of points.</P>
<DT><B> lum const <I>L</I> </B><DD><P>Specify constant particle luminosity <I>L</I> independent of
any data field values.</P>
</P>
<DT><B>fade [planar|spherical|linear <I>refdist</I>|const <I>refdist</I>]</B><DD><P>Determines how distance affects particles' apparent brightness (or "size").
The default <CODE>fade planar</CODE> gives 1/r^2 light falloff, with r measured
as distance from the view plane. <CODE>fade spherical</CODE> is also 1/r^2,
but with r measured as true distance from the viewpoint.
<CODE>fade linear</CODE> <I>refdist</I> gives 1/r light falloff -- not physically
accurate, but useful to get a limited sense of depth.
<CODE>fade const</CODE> <I>refdist</I> gives constant apparent brightness
independent of distance, and may be appropriate for orthographic views.</P>
<P>The <I>refdist</I> for linear and const modes is that distance <I>r</I>
at which apparent brightness should match that in the 1/r^2 modes --
a distance to a "typical" particle.</P>
<DT><B>labelmin <I>minpixels</I></B><DD><P>Labels computed to be smaller than this screen size (pixels) are suppressed.</P>
<DT><B>labelsize <I>scalefactor</I></B><DD>
<DT><B>lsize <I>scalefactor</I></B><DD><P>lsize (alias labelsize) sets the 3-D height of labels. If the text was created with a
<CODE>text -size </CODE><I>textsize</I> option, the scalefactor is multiplied by that to determine
the 3-D size.</P>
<DT><B>point[s] [on|off]</B><DD><P>Turn display of points on or off. With no argument, toggles display.</P>
<DT><B>poly[gons] [on|off]</B><DD><P>Turn display of points on or off. With no argument, toggles display.</P>
<DT><B>texture [on|off]</B><DD><P>Turn display of textures on or off. With no argument, toggles.</P>
<DT><B>label[s] [on|off]</B><DD><P>Turn display of label text on or off. With no argument, toggles.</P>
<DT><B>txscale <I>scalefactor</I></B><DD><P>Scale size of all textures relative to their polygons.
A scale factor of 0.5 (default) make the texture square
just fill its polygon, if <CODE>polysides</CODE> is 4.</P>
<DT><B>polyorivar</B><DD><P>Report setting of <CODE>polyorivar</CODE> data-command, which see.</P>
<DT><B>texturevar</B><DD><P>Report setting of <CODE>texturevar</CODE> data-command, which see.</P>
<DT><B>laxes [on|off]</B><DD><P>Toggle label axes. When on, and when labels are displayed,
shows a set of red/green/blue (X/Y/Z) axes to indicate orientation.</P>
<DT><B>polyside(s)</B><DD><P>Number of sides a polygon should have. Default 11, for fairly round
polygons. For textured polygons, <CODE>polysides 4</CODE> might do as well,
and be slightly speedier.</P>
<DT><B>fast [on|off]</B><DD><P>see also <CODE>ptsize</CODE></P>
<DT><B>ptsize <I>minpixels</I> [<I>maxpixels</I>]</B><DD><P>Specifies range of apparent (pixel) size of points.
Those with computed sizes (based on luminosity
and distance) smaller than <I>minpixels</I> are
randomly (but repeatably) subsampled -- i.e. some
fraction of them are not drawn. Those computed to be
larger than <I>maxpixels</I> are drawn at size
<I>maxpixels</I>.</P>
<DT><B>gamma <I>displaygamma</I></B><DD><P>Tells the particle renderer how the display + OpenGL
relates image values to visible lightness.
You don't need to change this, but may adjust it
to minimize the brightness glitches when particles change size.
Typical values are <CODE>gamma 1</CODE> through <CODE>gamma 2.5</CODE> or so.
Larger values raise the apparent brightness of dim things.</P>
<DT><B>alpha <I>alpha</I></B><DD><P>Get or set the alpha value, in the range 0 to 1; it determines
the opacity of polygons.</P>
<DT><B>speed</B><DD><P>For time-dependent data, advance datatime by this many time units
per wall-clock second.</P>
<DT><B>step [<I>timestep</I>]</B><DD><P>For time-varying data, sets current timestep number.
Real-valued times are meaningful for some kinds of data including those
from Starlab/kira; for others, times are rounded to nearest integer.
If running, <CODE>step</CODE> also stops datatime animation. (See <CODE>run</CODE>.)</P>
<DT><B>step [+|-]<I>deltatimestep</I></B><DD><P>If preceded with a plus or minus sign, adds that amount to current time.</P>
<P>(note that <CODE>fspeed</CODE> has been deprecated)</P>
<DT><B>run</B><DD><P>Continue a stopped animation (see also <CODE>step</CODE>).</P>
<DT><B>tfm [-v] [<I>numbers...</I>]</B><DD><P>Object-to-world transformation.
May take 1, 6, 7, 9 or 16 parameters: either
<I>scalefactor</I>,
or <I>tx ty tz rx ry rz </I><I>scalefactor</I>>],
or 16 numbers for 4x4 matrix,
or 9 numbers for 3x3 matrix.
See <I>Coordinates and Coordinate Transformations</I>.</P>
<P>With no numeric parameters, reports the current object-to-world transform.
Use <CODE>tfm -v</CODE> to see the transform and its inverse in several forms.</P>
<DT><B>move [g<I>N</I>] {on|off}</B><DD><P>Normally, navigation modes <CODE>[r]otate</CODE> and <CODE>[t]ranslate</CODE>
just adjust the viewpoint (camera). However,
if you turn <CODE>move on</CODE>, then <CODE>[r]otate</CODE> and <CODE>[t]ranslate</CODE>
move the currently-selected object group instead,
e.g. to adjust its alignment relative to other groups.
(<CODE>[o]rbit</CODE> and <CODE>[f]ly</CODE> modes always move the camera.)</P>
<P>To indicate that <CODE>move</CODE> mode is enabled,
the control strip shows the selected group's name in
bold italics, as <B><I>[g3]</I></B>.
Use <CODE>move off</CODE> to revert to normal.
The <CODE>tfm</CODE> command reports the current object-group-to-global-world
transformation.</P>
<DT><B>fwd</B><DD>
<DT><B>datawait on|off</B><DD><P>For asynchronously-loaded data (currently only <CODE>ieee</CODE> data command),
say whether wait for current data step to be loaded.
(If not, then keep displaying previous data while loading new.)</P>
<DT><B>cmap <I>filename</I></B><DD><P>Load (ascii) filename with RGB values, for coloring particles.
The <CODE>color</CODE> command selects which data field is mapped to color index
and how.</P>
<P>Colormaps are text files, beginning with a number-of-entries
line and followed by R G B or R G B A entries one per line;
see the <I>Colormaps</I> section.</P>
<DT><B>vcmap -v <I>fieldname</I> <I>filename</I></B><DD><P>Load colormap as with <CODE>cmap</CODE> command. But use this colormap
only when the given data field is selected for coloring.
Thus the <CODE>cmap</CODE> color map applies to all data fields for which
no <CODE>vcmap</CODE> has ever been specified.</P>
<DT><B>cment <I>colorindex</I> [<I>R G B</I>]</B><DD><P>Report or set that colormap entry.</P>
<DT><B>rawdump <I>dump-filename</I></B><DD><P>All particle attributes (not positions though)
are written to a <I>dump-filename</I>. Useful for debugging.
Warning: it will happily overwrite an existing file with that name.</P>
<DT><B>warp [on|off]</B><DD><P>Enable, disable, or report the status of any <CODE>warp</CODE> data-command set up for the current group.
If it exists, particles's positions can change with time, in a handful of canned ways
built into the <CODE>warp</CODE> command. See the <CODE>warp</CODE> entry under Data Commands.</P>
</P>
<H2><A NAME="ss4.6">4.6</A> <A HREF="partiview.html#toc4.6">Particle subsetting & statistics</A>
<DT><B>clipbox ...</B><DD><P>see <CODE>cb</CODE> below.</P>
<DT><B>cb ....</B><DD><P>Display only a 3D subregion of the data -- the part lying within the clipbox.
<DL>
<DT><B>cb <I>xmin ymin zmin xmax ymax zmax</I> </B><DD><P>Specified by coordinate ranges.
Note only spaces are used to separate the 6 numbers.</P>
<DT><B>cb <I>xcen,ycen,zcen xrad,yrad,zrad</I> </B><DD><P>Specified by center and "radius" of the box.
Note no spaces after the commas!</P>
<DT><B>cb <I>xmin,xmax ymin,ymax zmin,zmax</I> </B><DD><P>Specified by coordinate ranges.</P>
<DT><B>cb <CODE>off</CODE> </B><DD><P>Disable clipping. The entire dataset is again visible.</P>
<DT><B>cb <CODE>on</CODE> </B><DD><P>Re-enable a previously defined clipbox setting. It will also
display the clipbox again</P>
<DT><B>cb <CODE>hide</CODE> </B><DD><P>Hide the clipbox, but still discard objects whose centers
lie outside it.</P>
Note this command does not toggle clipping
if no arguments given (that would be handy
and more in line with similar commands).
If no arguments given, it reports the current clipbox.</P>
<DT><B>thresh</B><DD><P>Display a subset of particles, chosen by the value of
some data field. Each <CODE>thresh</CODE> command overrides
settings from previous commands, so it cannot be used to
show unions or intersections of multiple criteria.
For that, see the <CODE>only</CODE> command. However, unlike <CODE>only</CODE>,
the <CODE>thresh</CODE> criterion applies to time-varying data.
<DL>
<DT><B>thresh <I>field</I> <I>minval</I> <I>maxval</I> </B><DD><P>Display only those particles where
<I>minval</I> <= field <I>field</I> <= <I>maxval</I>.
The <I>field</I> may be given by name (as from <CODE>datavar</CODE>)
or by field number.</P>
<DT><B>thresh <I>field</I> <CODE><</CODE><I>maxval</I> </B><DD>
<DT><B>thresh <I>field</I> <CODE>></CODE><I>minval</I> </B><DD><P>Show only particles where <I>field</I> is <=
or >= the given threshold.</P>
<DT><B>thresh [off|on]</B><DD><P>Disable or re-enable a previously specified threshold.</P>
</P>
<DT><B>only= <I>datafield</I> <I>value</I> <I>minvalue-maxvalue</I> <<I>value</I> ><I>value</I> ...</B><DD>
<DT><B>only+ <I>datafield</I> <I>value</I> <I>minvalue-maxvalue</I> <<I>value</I> ><I>value</I> ...</B><DD>
<DT><B>only- <I>datafield</I> <I>value</I> <I>minvalue-maxvalue</I> <<I>value</I> ><I>value</I> ...</B><DD><P>Scans particles (in the current timestep only!), finding those where
<I>datafield</I> has value <I>value</I>, or has a value in range
<I>minvalue</I> <= value <= <I>maxvalue</I>, or whatever.
Multiple value-ranges may be specified to select the union of several sets.
The resulting set of particles is assigned to (<CODE>only=</CODE>), added to
(<CODE>only+</CODE>) or subtracted from (<CODE>only-</CODE>) the <CODE>thresh</CODE> selection-set.
Also display just particles in that selection-set, as if <CODE>see thresh</CODE>
had been typed.</P>
<P>The net effect is illustrated by these examples:
<DL>
<DT><B>only= type 1-3 5</B><DD><P>Show only particles of type 1, 2, 3 or 5.</P>
<DT><B>only- mass <2.3 >3.5</B><DD><P>After the above command, shows only the subset
of type 1/2/3/5 particles AND have mass between 2.3 and 3.5.
(Note that to take the intersection of two conditions,
you must subtract the complement of the latter one.
Maybe some day there'll be an <CODE>only&</CODE>.</P>
</P>
<DT><B>see <CODE>selexpr</CODE></B><DD><P>Show just those particles in the selection-set <CODE>selexpr</CODE>.
Predefined set names are <CODE>all</CODE>, <CODE>none</CODE>, <CODE>thresh</CODE> and <CODE>pick</CODE>,
and other names may be defined by the <CODE>sel</CODE> command.
The default is <CODE>see all</CODE>. Using the <CODE>thresh</CODE> or <CODE>only</CODE>
commands automatically switch to displaying <CODE>see thresh</CODE>.</P>
<P>Note that you can see the complement of a named set,
e.g. all except the <CODE>thresh</CODE>-selected objects, with
<CODE>see -thresh</CODE>.</P>
<DT><B>sel <CODE>selname = selexpr</CODE></B><DD><P>Compute a logical combination of selection-sets and assign them
to another such set. The set membership is originally assigned by
<CODE>thresh</CODE> or <CODE>only</CODE> commands. Yeah, I know this doesn't make sense.
Need a separate section to document selection-sets.</P>
<DT><B>sel <CODE>selexpr</CODE></B><DD><P>Count the number of particles in the selection-set <CODE>selexpr</CODE>.</P>
<DT><B>clearobj</B><DD><P>Erase all particles in this group. Useful for reloading on the fly.</P>
<DT><B>every <I>N</I></B><DD><P>Display a random subset (every <I>N</I>-th) of all particles.
E.g. <CODE>every 1</CODE> shows all particles, <CODE>every 2</CODE> shows about half of them.
Reports current subsampling factor, and the current total number of particles.</P>
<DT><B>hist <I>datafield</I> [-n <I>nbuckets</I>] [-l] [-c] [-t] [<I>minval</I>] [<I>maxval</I>]</B><DD><P>Generates a (numerical) histogram of values of <I>datafield</I>,
which may be a named field (as from <CODE>datavar</CODE>) or a field index.
Divides the value range (either <I>minval</I>..<I>maxval</I>
or the actual range of values for that field) into <I>nbuckets</I>
equal buckets (11 by default). Uses logarithmically-spaced
intervals if <CODE>-l</CODE> (so long as the data range doesn't include zero).
If a clipbox is defined, use <CODE>-c</CODE> to count only
particles within it. If a <CODE>thresh</CODE> or <CODE>only</CODE>
subset is defined, use <CODE>-t</CODE> to count only the chosen subset.</P>
<DT><B>bound [w]</B><DD><P>Reports 3D extent of the data. With <CODE>w</CODE>, reports it in
world coordinates, otherwise in object coordinates.</P>
<DT><B>datavar</B><DD>
<DT><B>dv</B><DD><P>Report names and value ranges (over all particles in current group)
of all named data fields.</P>
</P>
<H2><A NAME="ss4.7">4.7</A> <A HREF="partiview.html#toc4.7">Boxes</A>
<DT><B>showbox <I>list of integer box level numbers...</I></B><DD>
<DT><B>hidebox <I>list of integer box level numbers...</I></B><DD>
<DT><B>box[es] [off|on|only]</B><DD><P>Turn box display off or on; or display boxes but hide all particles.</P>
<DT><B>boxcmap <I>filename</I></B><DD><P>Color boxes using that colormap.
Each box's level number (set by <CODE>-l</CODE> option of <CODE>box</CODE> data-command,
default 0) is the color index.</P>
<DT><B>boxcment <I>colorindex</I> [<I>R G B</I>]</B><DD><P>Get or set the given box-colormap index. E.g. <CODE>boxcment 0</CODE>
reports the color of boxes created with no <CODE>-l</CODE> specified.</P>
<DT><B>boxlabel [on|off]</B><DD><P>Label boxes by id number
(set by <CODE>-n</CODE> option of <CODE>box</CODE> data-command).</P>
<DT><B>boxaxes [on|off]</B><DD><P>Toggle or set box axes display mode.</P>
<DT><B>boxscale [float] [on|off] </B><DD>
<DT><B>gobox <I>boxnumber</I></B><DD>
<DT><B>goboxscale</B><DD>
<DT><B>menu fmenu</B><DD>
<BLOCKQUOTE><CODE>
<PRE>
BEGIN CAVEMENU
pos P1 P2
wall P1
hid [P1]
show [P1]
h [P1]
demandfps [P1]
font
help
?
END CAVEMENU
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B>datascale</B><DD>
</P>
<H2><A NAME="ss4.8">4.8</A> <A HREF="partiview.html#toc4.8">Data commands </A>
<P>(see also partibrains.c::specks_read)</P>
<P>Data Commands can be placed in a data file.
Lines starting with <CODE>#</CODE> will be skipped. </P>
<P>Control Commands can also be given, if prefixed with the <CODE>eval</CODE> command.</P>
<DT><B>read <I>file</I> </B><DD><P>read a <CODE>speck</CODE> formatted file. Recursive, commands can nest. (strtok ok??)
Note that <CODE>read</CODE> is also a Control Command, doing exactly the same thing.</P>
<DT><B>include <I>file</I></B><DD><P>read a <CODE>speck</CODE> formatted file.</P>
<DT><B>ieee [-t time] <I>file</I></B><DD><P>Read a IEEEIO formatted file, with optional timestep number (0 based).
Support for this type of data must be explicitly compiled into the program.</P>
<DT><B>kira <I>file</I> </B><DD><P>read a <CODE>kira</CODE> formatted file. See the <CODE>kiractl</CODE> Control
Command to modify the looks of the objects. Only present if Starlab is compiled
into partiview.</P>
<DT><B>setenv name value</B><DD><P>Add (or change) a named variable of the environment variables space of
partiview. Enviroment variables, like in the normal unix shell, can be
referred to by prepending their name with a $.
<I>Note there probably is not an unsetenv command</I>.</P>
<DT><B>object <I>gN=ALIAS</I></B><DD><P>Defines/Selects a particular group number (N=1,2,3....) to an ALIAS. In
command mode you can use <CODE>gN=ALIAS</CODE>. Any data following this command
will now belong to this group.</P>
<DT><B>object <I>ObjectName</I></B><DD><P>Select an existing group. Following data will now belong to this group.</P>
<DT><B>sdbvars <I>var</I></B><DD><P>Choose which data fields to
extract from binary sdb files (any of: <CODE>mMcrogtxyzSn</CODE>) for subsequent
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<CODE>sdb</CODE> commands.</P>
<DT><B>sdb [-t time] <I>file</I></B><DD><P>Read an SDB (binary) formatted file, with optional timestep number.
(Default time is latest <CODE>datatime</CODE>, or 0.)</P>
<DT><B>pb [-t time] <I>file</I></B><DD><P>Read a <CODE>.pb</CODE> (binary) particle file, with optional timestep number.
(Default time is latest <CODE>datatime</CODE>, or 0.)
A <CODE>.pb</CODE> file contains (all values 32-bit integer or 32-bit IEEE float):
<OL>
<LI>magic number, 0xFFFFFF98 (int32)</LI>
<LI>byte offset of first particle (int32)</LI>
<LI>number of attributes (int32)</LI>
<LI>sequence of null-terminated attribute name strings,
attributename0 \0 attributename1 \0 ...</LI>
<LI>possibly some pad bytes, enough to reach the specified
first-particle file offset</LI>
<LI>sequence of particle records,
each (number-of-attributes + 4)*4 bytes long:
<OL>
<LI>particle-id (int32)</LI>
<LI>particle X, Y, Z (3 float32's) </LI>
<LI>particle attributes (number-of-attributes float32's)</LI>
</OL>
ending at the end of the file (i.e. there's no particle-count field).</LI>
</OL>
Either big- or little-endian formats are accepted; the value of the
magic number determines endianness of all values in that file.</P>
<DT><B>box[es] <I>....</I></B><DD><P>Draw a box, using any of the following formats:</P>
<DT><B> <CODE>xmin ymin zmin xmax ymax zmax</CODE> </B><DD>
<DT><B> <CODE>xmin,xmax ymin,ymax zmin,zmax</CODE> </B><DD>
<DT><B> <CODE>xcen,ycen,zcen xrad,yrad,zrad</CODE> </B><DD>
<DT><B> <CODE>[-t time] [-n boxno] [-l level] xcen,ycen,zcen xrad,yrad,zrad </CODE> </B><DD>
<CODE>level</CODE> determines color.</P>
<DT><B><CODE>mesh</CODE> [<CODE>-t</CODE> <I>txno</I>] [<CODE>-c</CODE> <I>colorindex</I>] [<CODE>-s</CODE> <I>style</I>]</B><DD><P>Draw a quadrilateral mesh, optionally colored or textured.
Following the <B>mesh</B> line, provide a line with the mesh dimensions:
nu nv</P>
<P>Following this comes the list of <I>nu</I>*<I>nv</I> mesh vertices,
one vertex (specified by several blank-separated numbers) per line.
(Blank lines and comments may be interspersed among them.)
Note that the mesh connections are implicit:
vertex number i*nu+j is adjacent to (i-1)*nu+j, (i+1)*nu+j, i*nu+(j-1),
and i*nu+(j+1). Each vertex line has three or five numbers:
the first three give its 3-D position, and if a <CODE>-t</CODE> texture was
specified, then two more fields give its u and v texture coordinates.</P>
<P>Options:
<DL>
<DT><B> <CODE>-t</CODE> <I>txno</I> </B><DD><P>Apply texture number <I>txno</I> to surface.
In this case, each mesh vertex should also include
u and v texture coordinates.</P>
<DT><B> <CODE>-c</CODE> <I>colorindex</I> </B><DD><P>Color surface with color from
integer cmap entry <I>colorindex</I>.</P>
<DT><B> <CODE>-s</CODE> <I>style</I> </B><DD><P>Drawing style:
<DL>
<DT><B> <I>solid</I> </B><DD><P>filled polygonal surface (default)</P>
<DT><B> <I>wire</I> </B><DD><P>just edges</P>
<DT><B> <I>point</I> </B><DD><P>just points (one per mesh vertex)</P>
</P>
</P>
<DT><B><I>Xcen Ycen Zcen</I> ellipsoid <I>[options]... [transformation]</I></B><DD><P>Draw an ellipsoid, specified by:
<DL>
<DT><B> <CODE>Xcen Ycen Zcen</CODE> </B><DD><P>Center position in world coordinates</P>
<DT><B> <CODE>-c</CODE> <I>colorindex</I> </B><DD><P>Integer color index (default -1 => white)</P>
<DT><B> <CODE>-s</CODE> <I>style</I> </B><DD><P>Drawing style:
<DL>
<DT><B> <I>solid</I> </B><DD><P>filled polygonal surface (default)</P>
<DT><B> <I>plane</I> </B><DD><P>3 ellipses: XY, XZ, YZ planes</P>
<DT><B> <I>wire</I> </B><DD><P>latitude/longitude ellipses</P>
<DT><B> <I>point</I> </B><DD><P>point cloud: one per lat/lon intersection</P>
</P>
<DT><B> <CODE>-r</CODE> <I>Xradius</I>[,<I>Yradius</I>,<I>Zradius</I>] </B><DD><P>Radius (for sphere) or semimajor axes (for ellipsoid)</P>
<DT><B> <CODE>-n</CODE> <I>nlat[,nlon]</I> </B><DD><P>Number of latitude and longitude divisions.
Relevant even for <I>plane</I> style, where they determine
how finely the polygonal curves approximate circles.
Default <I>nlon</I> = <I>nlat</I>/2 + 1.</P>
<DT><B> <I>transformation</I> </B><DD><P>Sets the spatial orientation of the ellipsoid.
May take any of three forms:
<DL>
<DT><B> (nothing) </B><DD><P>If absent, the ellipsoid's
coordinate axes are the same as the world axes
for the group it belongs to.</P>
<DT><B> 9 blank-separated numbers </B><DD><P>A 3x3 transformation matrix T from ellipsoid coordinates
to world coordinates, in the sense
Pworld = Pellipsoid * T + [Xcen, Ycen, Zcen].</P>
<DT><B> 16 blank-separated numbers </B><DD><P>A 4x4 transformation matrix, as above but for the
obvious changes.</P>
</P>
</P>
<DT><B>waveobj [-time <I>timestep</I>] [-static] [-texture <I>number</I>] [-c <I>colorindex</I>] [-s <I>style</I>] <I>file.obj</I></B><DD><P>Load a Wavefront-style .obj model. Material properties are
ignored; the surface is drawn in white unless <CODE>-c</CODE> <I>colorindex</I>
in which case it's drawn using that color-table color.
Also if <CODE>-texture</CODE> (alias <CODE>-tx</CODE>) is supplied,
the surface is textured using whatever texture coordinates are
supplied in the .obj file. The model is displayed at all times
only if marked <CODE>-static</CODE>; otherwise it's displayed only
at the time given by <CODE>-time</CODE> <I>timestep</I> or by the most recent <I>datatime</I>.</P>
<P>A subset of the .obj format is accepted:
<DL>
<DT><B>v <I>X Y Z</I></B><DD><P>-- vertex position</P>
<DT><B>vt <I>U V</I></B><DD><P>-- vertex texture coordinates</P>
<DT><B>vn <I>NX NY NZ</I></B><DD><P>-- vertex normal</P>
<DT><B>f <I>V1 V2 V3 ...</I></B><DD><P>-- face, listing just position indices for each vertex.
The first <CODE>v</CODE> line in the .obj file has index 1, etc.</P>
<DT><B>f <I>V1/T1 V2/T2 V3/T3 ...</I></B><DD><P>-- face,
listing position and texture coordinates for each vertex of the face.</P>
<DT><B>f <I>V1/T1/N1 V2/T2/N2 V3/T3/N3 ...</I></B><DD><P>-- face,
listing position, texture-coordinate, and normal indices for each vertex.</P>
</DL>
Note that material properties (mtl) are ignored. Waveobj models are colored
according to the <CODE>-c</CODE> <I>colorindex</I> option (integer index
into the current <CODE>cmap</CODE> colormap), or white if no <CODE>-c</CODE> is used.
If texturing is enabled -- if the .obj model contains <CODE>vt</CODE> entries,
and the <CODE>-texture</CODE> option appears, and that numbered texture exists --
then the given texture color multiplies or replaces the <CODE>-c</CODE> color,
according to the texture options.</P>
<DT><B>tfm [camera] <I>numbers...</I></B><DD><P>Object-to-world transformation.
May take 1, 6, 7, 9 or 16 numbers: either
<I>scalefactor</I> or
<I>tx ty tz rx ry rz </I>[it/scalefactor/]
or 16 numbers for 4x4 matrix,
or 9 numbers for 3x3 matrix.
See <I>Coordinates and Coordinate Transformations</I>.</P>
<P>Normally the transform is to world coordinates;
but with optional <CODE>camera</CODE> prefix, the object's position
is specified relative to the camera, useful to place
legends in a fixed position on the screen.
In camera coordinates, (0,0,0) is the viewpoint,
x=y=0 at screen center, and negative z extends forward.
Try for example
<PRE>
tfm camera -3 -3 -20 0 0 0
0 0 0 text -size 20 Legend
</PRE>
</P>
<DT><B>eval <I>command</I></B><DD><P>execute a Control Command.</P>
<DT><B>feed <I>command</I></B><DD><P>Synonym for <CODE>eval</CODE>.</P>
<DT><B>VIRDIR <I>command</I></B><DD><P>Synonym for <CODE>eval</CODE>.</P>
<DT><B>filepath <I>path</I></B><DD><P>A colon-separated list of directories in which datafiles, color maps, etc.
will be searched for. If preceded with the <CODE>+</CODE> symbol,
this list will be appended to the current <I>filepath</I>.</P>
<DT><B>polyorivar <I>indexno</I></B><DD><P>By default, when polygons are drawn, they're parallel to the screen plane --
simple markers for the points. It's sometimes useful to give each
polygon a fixed 3-D orientation (as for disk galaxies). To do this,
provide 6 consecutive data fields, representing two 3-D orthogonal unit
vectors which span the plane of the disk. Then use
<CODE>polyorivar </CODE><I>indexno</I>
giving the data field number of the first of the 6 fields.
The vectors define the X and Y directions on the disk, respectively --
relevant if texturing is enabled.</P>
<P>Actually, unit vectors aren't essential; making them different lengths
yields non-circular polygonal disks. </P>
<P>If <CODE>polyorivar</CODE> is specified for the group, but some polygons should
still lie in the screen plane, use values <CODE>9 9 9 9 9 9</CODE> for those polygons.</P>
<DT><B>texture [-aiAOlmnMDB] <I>txno file.sgi</I> </B><DD><P>
<DT><B> -a(lpha) </B><DD><P>A single-channel image would normally be used as luminance data.
With <CODE>-a</CODE>, the image is taken as opacity data instead
(GL_ALPHA texture format).</P>
<DT><B> -i(ntensity) </B><DD><P>For 1- or 3-channel images, compute the intensity of each pixel
and use it to form an alpha (opacity) channel.</P>
<DT><B> -A(dd) </B><DD><P>Use additive blending. This texture will add to, not obscure,
the brightness of whatever lies behind it (i.e. whatever is drawn later).</P>
<DT><B> -O(ver) </B><DD><P>Use "over" compositing. This texture will obscure features lying
behind it according to alpha values at each point.</P>
<DT><B> -M(odulate) </B><DD><P>Multiply texture brightness/color values by the colormap-determined
color of each particle.</P>
<DT><B> -D(ecal) </B><DD><P>The textured polygon's color is determined entirely by the texture,
suppressing any colormapped color.</P>
<DT><B> -B(lend) </B><DD><P>Probably not very useful.</P>
</P>
<DT><B>texturevar <I>field</I></B><DD><P>If polygon-drawing and texturing are turned on, use the given
<I>field</I> (datavar name or number) in each particle to select
which texture (if any) to draw on its polygon.</P>
<DT><B>coord <I>name ... 16 world-to-coord tfm floats (GL order)</I></B><DD>
<DT><B>dataset <I>indexno datasetname</I></B><DD><P>Give names to multiple datasets in IEEEIO files (read with <CODE>ieee</CODE> command).
<I>indexno</I> is an integer, 0 being the first dataset.</P>
<DT><B>datavar <I>indexno name [minval maxval]</I></B><DD><P>Name the variable in data field <I>indexno</I>. The first data field has
<I>indexno</I> 0.
If provided, <I>minval maxval</I> supply the nominal range of that data variable;
some control commands (<CODE>lum</CODE>, <CODE>color</CODE>) need to know the range of data
values, and will use this instead of measuring the actual range.</P>
<DT><B>datatime <I>time</I></B><DD><P>Label subsequent data with this <I>time</I> (a non-negative integer).</P>
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<DT><B>warp</B><DD><P>When 'warp' has been defined for a group,
all its particles get their positions (re)computed according to
(a) the warp data-command's parameters, (b) the current time, (c) the particle's
initial position, and (d) maybe some attributes of each particle.</P>
<P>There are several (mutually exclusive) kinds of warping available:
<UL>
<LI> for doing a sort of differential rotation for disk-like galaxies;</LI>
<LI> for doing N-D to 3-D projection, where particle positions are replaced with
(time-independent) linear combinations of attribute values;</LI>
<LI> linear or polynomial extrapolation of the particle position with time,
with coefficients specified as triples of attributes</LI>
</UL>
</P>
<P>Options to <CODE>warp</CODE> data command:
<DL>
<DT><B>-p period0[f|s]</B><DD><P>"Rotation period". Sets timescale of motion, in frames (f) or seconds (s). </P>
<DT><B>-extrap coef0[,degree]]</B><DD><P>Extrapolate position with time. Velocity is given by attribute coef0 and the two attributes following it
(coef0 .. coef0+2), in the sense p = p_0 + [coef0 .. coef0+2] * (time/period0).
If <I>degree</I> given (default 1), uses 3*<I>degree</I> attributes as polynomial coefficients, as
p=p0+(t/period0)*field[coef0..coef0+2]+(t/period0)^2*[coef0+3..coef0+5]+...</P>
<DT><B>-sheet ampl,xlength,zlength</B><DD><P>For disk galaxy style: Applies exponential sheet warp for disk lying in the X-Z plane.
Scale set by xlength and zlength, Y-displacement set by ampl.</P>
<DT><B>-f fin,fout</B><DD><P>For disk-galaxy style: gives time range over which warp applies. </P>
<DT><B>-z zerotime</B><DD><P>For disk galaxy style: sets time at which particles are in their original positions.</P>
<DT><B>-R rot[,drot]</B><DD><P>Disk galaxy style: Add constant to rotation angle.</P>
<DT><B>-T o2d</B><DD><P>Provide object-to-disk coordinate transform (in "disk" coordinates, the disk lies in X-Z plane).
9 or 16 numbers.</P>
<DT><B>-F d2o</B><DD><P>Provide disk-to-object transform. 9 or 16 numbers.</P>
<DT><B>-r rcore[,transition][w]</B><DD><P>Disk galaxy style: set radius of rigidly-rotating inner region, and transition to constant-velocity region</P>
<DT><B>-fix x,y,z[w]|radius[w]</B><DD><P>Disk galaxy style: Keep the given 3-D point, or a point at the given disk radius, fixed.
E.g. track the sun.</P>
<DT><B>-galaxy gorbcoef0</B><DD><P>Special disk galaxy style. Each star is on its own disk-galaxy-like orbit,
with 8 orbital parameters given by 8 consecutive attributes starting with gorbcoef0.
See galaxyorbit.h (read the source).</P>
<DT><B>-ride speckno</B><DD><P>Ride along with speckno'th particle in first loaded group (displace particles by the difference
between their computed orbit position and the ridden-on particle).</P>
</DL>
</P>